retina lies in the back of the eye and is a multi-layered tissue which
detects visual images. These images are transmitted to the brain through
approximately 1 million tiny nerve fibers. These nerve fibers converge
in the back of the eye, before going to the brain, into a bundle called
the optic nerve. If some or all of the nerve fibers are damaged, visual
When the optic nerve becomes inflamed, this condition is called optic
neuritis. The nerve tissue becomes swollen and red, and the nerve fibers
do not work properly. If many of the nerve fibers are involved, the
vision may be dramatically affected, but if the optic neuritis is mild,
vision is nearly normal. Optic neuritis can be caused by many diseases
and conditions and may affect the optic nerve of one or both eyes.
Some people, especially children, develop optic neuritis following a
virus illness such as mumps, measles, or a cold. In others, optic neuritis
may occur as a sign of a neurologic disease affecting nerves in various
parts of the body, such as multiple sclerosis. In a rare condition called
Leber's optic neuropathy, which often runs in families, a special kind
of optic neuritis may appear in both eyes within a short span of time.
Most of the time, however, the cause for optic neuritis is unknown.
In those cases, the eye disorder is called neuritis idiopathic, meaning
that no particular cause can be found.
Optic neuritis usually comes on suddenly, and the patient notices vision
is blurred in one or both eyes. The vision is dim, like somebody turned
down the lights, and colors may appear to be washed out. There may be
pain in the area of the eye socket, especially when moving the eyes.
The vision may continue to get worse over a week or two, and may seem
worse after exercising or a hot bath.
A careful description of these symptoms is important to your doctor
for the diagnosis of optic neuritis. The optic nerve enters the back
of the eye where it appears as a small disc. Your eye doctor can examine
the optic nerve inside the eye by using a special instrument called
an ophthalmoscope. Swelling of the optic nerve may or may not be visible.
If the optic nerve inflammation occurs inside the eye, it can be readily
detected. If swelling of the nerve occurs behind the eye, the doctor
may not be able to see the swollen nerve tissue.
Since optic neuritis can be confused with many other causes of poor
vision, an accurate medical diagnosis is important. Ultrasound, CT scans
or visual brain wave recordings might be ordered. Other tests which
may be performed include color vision, side vision, and pupil reactions
Unfortunately, there is no good treatment for optic neuritis. Cortisone-like
medications (steroids) can be prescribed, but in most cases they are
not effective. In many cases, patients with optic neuritis improve without
treatment. The vision may return to normal or, in some cases, good but
incomplete improvement occurs. A few patients fail to recover normal
vision, especially those with special conditions.